Re: ERROR: ORDER/GROUP BY expression not found in targetlist

On Tue, Jun 14, 2016 at 2:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > In practice, we don't yet have the ability for
> > parallel-safe paths from subqueries to affect planning at higher query
> > levels, but that's because the pathification stuff landed too late in
> > the cycle for me to fully react to it.
>
> I wonder if that's not just from confusion between subplans and
> subqueries.
>

Won't the patch as written will allow parallel-restricted things to be
pushed to workers for UNION ALL kind of queries?

Explain verbose Select * from (SELECT c1+1 FROM t1 UNION ALL SELECT c1+1
FROM t2 where c1 < 10) ss(a);

In above kind of queries, set_rel_consider_parallel() might set
consider_parallel as true for rel, but later in set_append_rel_size(), it
might pull some unsafe clauses in target of childrel. Basically, I am
wondering about the same problem as we discussed here [1].

[1] -
https://www.postgresql.org/message-id/CAA4eK1Jz5tG2D2PCNYqYob2cb4dKowKYwVJ7OmP5vwyRyCMx4g%40mail.gmail.com

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com